The concept and function of geothermal energy systems is known in the art. The basic operation of geothermal energy system requires a “Hot Sedimentary Aquifer” that can be accessed by a deep borehole and the hot fluid (“primary working fluid”) extracted to the surface through cased production wells for heat extraction through an above-ground heat exchanger, the spent aquifer water is pumped back into the reservoir to recharge the reservoir through a separate injection well. The heat removed in the heat exchanger is then used in, e.g. a Rankin Cycle power plant or similar to produce electrical energy.
Another form of geothermal energy systems is the “Enhanced Geothermal System” where brine (“primary working fluid”) is injected into several (2 to 4) injection wells that access hot dry rock in the targeted reservoirs (typically through a series of reservoir fracturing to increase contact area between the hot dry rock and the brine) well below the surface and heat is transferred into the brine where it is recovered through a production well which is the remotely located from the injection well, to the surface. The recovered hot brine (typically in 2 phase flow of steam and hot water) is passed through a heat exchanger to extract heat for use in, e.g. a Rankin Cycle power plant or similar.
In each of these systems a suitably porous and permeable reservoir must be found to facilitate the circulation of the primary working fluid. This substantially restricts the reservoir numbers unless reservoir fracturing is employed, which is time consuming and costly and largely unpredictable. In addition, the open well configuration of both systems suffer from significant well scaling and corrosion which severely limits performance and at times lead to catastrophic failures.
Accordingly, there is a need for a geothermal energy system that can mitigate the scaling and corrosion problems as well as overcoming reservoir porosity and permeability limitations.
It will be understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge.